1. Field of the Invention
The present invention relates generally to shock attenuating devices for firearms. More particularly, the invention relates to a pad to reduce recoil force felt by a firearm user.
2. Description of the Prior Art
Recoil pads have been used for more than a century on shoulder-fired firearms to disperse the force generated during firing. Ammunition developments over the years have resulted in higher projectile velocities and projectile weights. These developments combined with lighter gun weights have led to a sometimes wearisome and painful increase in recoil force felt by the user. Although the increase in this "felt recoil" occurs in all shoulder-fired firearms, the problem particularly is troubling for shotgun shooters using heavy loads such as turkey magnums or heavy water fowl loads.
Recoil pads serve secondary functions in addition to those discussed above. For example, they may also be used to adjust stock length and prevent the firearm from slipping on the shoulder during firing.
The history of firearm design has seen many different approaches to recoil pad design. Early efforts were directed to attaching a soft material such as rubber at the end of the gun stock. Solid rubber pads are still commonly used for addressing felt recoil. Rubber provides some amount of dampening and dissipation of recoil force, but does not absorb recoil. Solid rubber recoil pads are available in a variety of degrees of cross link density values so that the pads may vary from being quite compressible to very hard. The softer rubber pads have the disadvantage of being unstable and susceptible to hardening with exposure to sunlight and heat. Also, soft rubber will smudge garments and attract dirt. Harder rubber compositions do not suffer as much from this disadvantage. Solid rubber recoil pads may be sanded to conform to the shape of a firearm stock.
Vented rubber recoil pads were intended to overcome the problems with solid rubber pads by providing energy absorbing voids in the pad structure. The open, relatively thin-walled structures were designed to compress under the firearm's recoil force in a controlled manner in an effort to absorb the recoil force and lessen the felt recoil. The voids or open structures may be open and visible to the shooter or may be hidden inside the pad, such as those made by Pachmayr, Ltd., of Monrovia, Calif. Vented rubber pads offer improved performance over rubber pads but at a tradeoff of higher manufacturing costs. Moreover, the thin-walled structures making up the void areas deteriorate with use.
Yet another approach is an attempt to redirect the force, such as the use of a thin fluid in an open cellular structure. This arrangement attempts to direct some of the forces normal to the direction of recoil via fluid flow and absorb them through frictional losses within the fluid. Unfortunately, the amount of force redirection is limited because fluid transport within the structure is small. Large fluid transport could occur by using a thin bag of water with no cellular structure to restrict flow. Under this arrangement, however, the fluid is transported too quickly resulting in a higher felt recoil force at the end of the rearward stroke. If this fluid could be viscoelastic with an appropriate amount of elasticity, the felt recoil could be reduced by redirecting the force and keep the felt recoil low through the entire recoil event.
These prior solutions have not succeeded in optimally reducing the felt recoil, while keeping the recoil pad simple and lightweight. While solid recoil pads have some advantages and could reduce recoil by adding to the overall weight of the firearm, disadvantages result as well. Heavy recoil pads increase the overall weight of the firearm and can impact adversely the firearm's accuracy by shifting the balance of the firearm rearwardly. Compressible recoil pads do not reduce the amount of force generated during firing, but change the characteristics of how that force is felt by the shooter. As these types of pads compress, they transform the sharp instantaneous push of the recoil force into a more attenuated sensation. As the recoil pad compresses, it permits the comb of the firearm stock to move rearwardly along the shooter's cheekbone. This rearward movement is sometimes referred to in the art as "face slap" and, if excessive, can be quite uncomfortable for the shooter. Moreover, excessive rearward travel of the entire firearm during firing negatively affects accuracy.
There remains a need then for a recoil pad that is functional, simple, lightweight and attractive to users, and that also reduces the felt recoil.